Extrusion-based additive manufacturing method

ABSTRACT

A printer head ( 200, 300, 400 ) for a 3D-printing apparatus, comprising a nozzle ( 210, 310, 450 ) arranged to deposit one or more adjacently arranged filaments of printing material to form at least one layer of an object to be produced. The nozzle comprises at least one exterior surface ( 220 ) configured to be brought into abutting contact with a peripheral edge ( 280 ) of the at least one layer, and configured to be guided along the peripheral edge of the at least one layer and on a predetermined distance into the at least one layer.

FIELD OF THE INVENTION

The present invention generally relates to the field of additivemanufacturing, which is sometimes also referred to as 3D printing. Morespecifically, the present invention relates to an extrusion-basedadditive manufacturing method for manufacturing an object using a3D-printing apparatus. The present invention also relates to a computerprogram and to a computer-readable data carrier having stored thereonthe computer program, wherein the computer program comprisesinstructions which, when the program is executed by a 3D-printingapparatus, cause the 3D-printing apparatus to carry out the steps of themethod.

BACKGROUND OF THE INVENTION

Additive manufacturing, sometimes also referred to as 3D printing,refers to processes used to synthesize a three-dimensional object. 3Dprinting is rapidly gaining popularity because of its ability to performrapid prototyping without the need for assembly or molding techniques toform the desired article.

The object may be formed using a 3D-printing apparatus that builds theobject in three dimensions in a number of printing steps that areusually controlled by a computer model. For example, a sliced 3D modelof the object may be provided in which each slice is recreated by the3D-printing apparatus in a discrete printing step. The 3D-printingapparatus may deposit successive layers of an extrudable material from adispenser, and the layers may be cured or otherwise hardened afterdeposition, e.g. using a laser to induce the curing process.

An example of a 3D-printing apparatus is disclosed in US 2010/0327479A1. This 3D-printing apparatus is an extrusion-based additivemanufacturing system that can be used to build a 3D object from adigital representation of the 3D object in a layer-by-layer manner byextruding a flowable consumable modeling material filament through anextrusion tip carried by an extrusion head, and by depositing themodeling material on a substrate. This extrusion-based additivemanufacturing method is also referred to as fused deposition modeling,fused layer modeling, or fused filament fabrication.

The majority of consumer 3D printers for performing the aforementionedextrusion-based additive manufacturing method comprise a moving headinto which a plastic filament is fed. However, printers of this kind maysuffer from the drawback of manufacturing objects which often showimperfections as a result of the method of deposition. For example,these imperfections may include ridges and/or stepped structures, alsoreferred to as “staircase” structures, as a result of successivedeposition of individual filaments onto a previously set filament layer.Ridges may occur as the deposited material at its edges can flow due tominimal surface tension, resulting in rounded edges.

Ridges and/or staircase structures may not only be detrimental to thestructural integrity (creating many initiators for cracks anddelamination) and overall part tolerances of the printed object, theymay also be aesthetically unpleasing. To avoid this, methods forsmoothing the surfaces have been suggested, e.g. by means of solventvapors, paintings and/or coatings. However, a significant drawback ofthese methods is that they require one or more extra processing steps.

Hence, alternative solutions are of interest which are able to eliminateor reduce ridges and/or staircase structures of 3D-printed objects, suchthat the objects produced may become more stable, more easily integratedand/or more aesthetically pleasing.

SUMMARY OF THE INVENTION

It is an object of the present invention to mitigate the above problemsand to provide a method for creating objects by means of extrusion-basedadditive manufacturing (3D printing), wherein the objects so producedhave improved stability, integration and/or visual properties comparedto objects produced by extrusion-based additive manufacturing (3Dprinting) according to the prior art.

According to a first aspect of the present invention, there is provideda method of smoothing the peripheral edge of one of more layerscomprising one or more adjacently arranged filaments of printingmaterial. The method is an extrusion-based additive manufacturing methodfor manufacturing an object using a 3D-printing apparatus, wherein the3D-printing apparatus comprises a nozzle arranged to deposit one or moreadjacently arranged filaments of printing material, and wherein thenozzle comprises at least one exterior surface. The method comprises thestep of depositing the one or more adjacently arranged filaments ofprinting material to form at least one layer of the object. The methodfurthermore comprises the steps of bringing the at least one exteriorsurface of the nozzle into abutting contact with the peripheral edge ofthe at least one layer and guiding the nozzle along the peripheral edgeof the at least one layer and on a predetermined distance into the atleast one layer.

Thus, the present invention is based on the idea of providing a printerhead for a 3D-printing apparatus which is configured to print at leastone layer comprising one or more filaments of printing material, andthen smooth out the at least one layer. In other words, after depositingone or more adjacently arranged filaments of printing material, thenozzle itself is used for smoothening out the layer(s), as the exteriorsurface(s) of the nozzle may be guided along the peripheral edge(s) ofthe layer(s) after the layer(s) has (have) been printed.

The present invention is advantageous in that the nozzle of the printerhead may function both as an extruder and as a smoothening element. Inother words, an object may be printed by the printer head, and anyoccurring ridges and/or staircase structures may hereby be smoothenedwithout any additional processing steps after printing including solventvapors, paintings and/or coatings. The present invention hereby providesa cost- and/or time-saving operation by the printer head.

The present invention is further advantageous in that ridges and/orstaircase structures of 3D-printed objects may be convenientlyeliminated or reduced by the printer head after printing, such that theobjects produced by the 3D-printing apparatus may become more stable,more easily integrated and/or more aesthetically pleasing.

The printer head of the 3D-printing apparatus used in the methodaccording to the present invention comprises a nozzle arranged todeposit one or more adjacently arranged filaments of printing materialto form at least one layer of an object to be produced. Hence, a layermay comprise one filament (i.e. string) of printing material to form alayer, or a plurality of filaments of printing material arrangedadjacently to form a layer. By “printing material”, it is here meant amaterial which can be extruded, e.g. an extruded plastic material. Thenozzle comprises at least one exterior surface configured to be broughtinto abutting contact with the peripheral edge of the at least onelayer. By “exterior surface”, it is here meant an outside surface orside portion of the nozzle. The nozzle is furthermore configured to beguided along the peripheral edge of the layer(s). By “peripheral edge”,it is here meant an outer (side) edge of the layer(s). The nozzle isfurthermore configured to be guided on a predetermined distance into theat least one layer. In other words, the nozzle is configured to be ledand/or pressed into the layer(s) of the printed material, which are tobe smoothened.

At least a portion of the peripheral edge of the at least one layer maycomprise a semi-spherical shape which projects in the plane of the atleast one layer, and the predetermined distance may correspond to aradius of the semi-spherical shape. Hence, in the method the nozzle maybe guided along the peripheral edge of the at least one layer such thatthe radius of a layer having a semi-spherical shape is smoothened. Thisis advantageous in that the nozzle is guided along the layer edge(s)into an appropriate distance into the layer material, such that layeredges may be conveniently flattened.

The nozzle of the 3D-printing apparatus used in the method according tothe invention may elongate along a first axis and while performing themethod the nozzle may be guided a predetermined distance along the firstaxis. In other words, the method comprises the step of guiding thenozzle in the same direction as its elongation (which commonly is in avertical direction). This is advantageous in that the peripheral edge ofthe layer(s) may be conveniently smoothened, e.g. in a verticaldirection.

The nozzle of the 3D-printing apparatus used in the method according tothe invention may elongate along a first axis and the at least oneexterior surface may comprise at least one plane which is parallel tothe first axis. Hence, the exterior surface of the nozzle, which broughtinto abutting contact with the peripheral edge of the layer(s) whileperforming the method, may comprise one or more planes. This isadvantageous in that the nozzle efficiently and conveniently smoothensout the layer edge(s) by one or more of its plane side portions.

The at least one exterior surface of the nozzle may comprise at leastone surface area of a spherical sector of the nozzle. This isadvantageous in that the nozzle hereby is configured to efficiently andconveniently smoothen out edges of the layer which also are inclinedwith respect to the elongation of the nozzle. In other words, the nozzleis configured to offer more freedom in smoothening inwards and/oroutwards sloping walls.

The nozzle of the 3D-printing apparatus used in the method according tothe invention may elongate along a first axis and may have a cylindershape. This is advantageous in that the nozzle hereby is configured toefficiently and conveniently smoothen out edge(s) of the layer whichperipheral edge is rounded.

The method according to the invention may further comprise the step ofcooling the nozzle at least during the step of guiding of the nozzlealong the peripheral edge of the at least one layer and on apredetermined distance into the at least one layer. For this purpose,the printer head of the 3D-printing apparatus used in the method maycomprise a cooling unit which is in thermal contact with the nozzle andconfigured to cool the nozzle. By the term “cooling unit”, it is heremeant substantially any cooling unit, device, or the like, whichfurthermore is configured to cool the nozzle. This is advantageous inthat the cooling of the nozzle may reduce the adhesion between thenozzle and the printed material during the guiding of the nozzle alongthe peripheral edge of the layer(s). The smoothening of the peripheraledge of the layer(s) may hereby be performed more efficiently.

The nozzle of the 3D-printing apparatus used in the method according tothe invention may comprise a coating arranged to reduce the adhesionbetween the nozzle and the peripheral edge of the at least one layer.This is advantageous in that the nozzle may be guided along theperipheral edge of the layer(s) in an even more efficient way. Thecoating may comprise polytetrafluoroethylene, Teflon, or the like.

The nozzle of the 3D-printing apparatus used in the method according tothe invention may be tiltable. In other words, the nozzle may beconfigured to be tilted, inclined, or the like. This is advantageous inthat the tiltable nozzle may efficiently smoothen one or more layeredges which are inclined, e.g. those of a curved object.

In a second aspect of the present invention, there is provided acomputer program comprising instructions which, when the program isexecuted by a 3D-printing apparatus, cause the 3D-printing apparatus tocarry out the steps of the method according to the first aspect of thepresent invention.

In a third aspect of the present invention, there is provided acomputer-readable data carrier having stored thereon the computerprogram according to the second aspect of the present invention.

Further objectives of, features of, and advantages with, the presentinvention will become apparent when studying the following detaileddisclosure, the drawings and the appended claims. Those skilled in theart will realize that different features of the present invention can becombined to create embodiments other than those described in thefollowing.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other aspects of the present invention will now be described inmore detail, with reference to the appended drawings showingembodiment(s) of the invention.

FIG. 1 is a schematic view of a printer head and a deposition ofprinting material by such a printer head according to the prior art,

FIG. 2 is a schematic view of a printer head and a smoothening ofprinting material deposited by the printer head according to anexemplifying embodiment of the present invention,

FIG. 3 is a schematic view of a printer head suitable for use in themethod of the present invention, and

FIG. 4 is a schematic view of a printer head and a smoothening of layersof an object by the printer head, according to an exemplifyingembodiment of the present invention, and

FIG. 5 is a schematic flow chart diagram of a method according to anexemplifying embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a schematic view of a typical printer head 100 and adeposition of printing material 110 by such a printer head according tothe prior art. The nozzle 120 of the printer head 100 is tapered inshape. The printing material, e.g. a molten plastic, is extruded fromthe bottom portion of the nozzle 120 and is provided as filaments whichconstitute one or more layers 110.

FIG. 2 is a schematic view of a printer head 200 of a 3D-printingapparatus (not shown) that can be used in the method of the presentinvention. The printer head 200 comprises a nozzle 210 arranged todeposit one or more adjacently arranged filaments of printing materialto form at least one layer 250 of an object to be produced by the3D-printing apparatus. The nozzle 210, which in FIG. 2 elongates along afirst axis A, comprises at least one exterior surface 220. Here, theexterior surface 220 comprises a form of a plane B which is parallel tothe first axis A. After the printer head 200 has deposited the printingmaterial into a layer 250, similarly to the deposition as shown in FIG.1, the nozzle 210 is configured to be brought into abutting contact withthe peripheral edge 280 of the layer 250. It will be appreciated thatduring this process, the nozzle 210 is not configured to dispense anyprinting material. The movement of the printer head 200 to come into theabutting contact with the printing material is indicated by the arrow E,being perpendicular to axis A. Hence, the movement of the printer head200 as exemplified by the arrow E is parallel to the plane of the layer250. The nozzle 210 is further configured to be guided along theperipheral edge 280 of the layer 250 and on a predetermined distance dinto the layer 250. Hence, after each layer 250 has been printed, thenozzle 210 makes another pass over the print path, and the nozzle 210 ismoved inwards (indicated by the arrow E) and downwards (indicated by thearrow F). In FIG. 2, the peripheral edge 280 of the layer 250 comprisesa semi-spherical shape which projects in the plane of the layer 250, andthe predetermined distance d corresponds to the radius of thissemi-spherical shape. In other words, the predetermined distance d maycorrespond to the amplitude of the rounded profile of the peripheraledge 280 of the layer 250. The nozzle 210 may furthermore be configuredto be guided a predetermined distance c in the direction as indicated byarrow F (i.e. parallel to the first axis A). Here, the distance ccorresponds to the thickness of a layer 250, but it should be noted thatc may correspond substantially any distance, e.g. to the thickness of aplurality of layers 250. Hence, the printer head 200 may be configuredto first print at least one layer 250 and, subsequently, to smoothen outthe at least one layer 250 by at least one of the movements of thenozzle 210 in one or both of the directions as indicated by arrows E andF. In other words, the nozzle 210 may be used both as an extruder and asa smoothening element. The nozzle 210 may be used for smoothening outthe deposited layer(s) 250, wherein the exterior surface(s) 220 of thenozzle 210 may be guided along the peripheral edge(s) 280 of thelayer(s) 250 after the layer(s) 250 has (have) been printed.

It will be appreciated that the printer head 200 may furthermorecomprise a wheel in the shape of a cylinder rotationally coupled to thenozzle 210, and configured to rotate around the nozzle 210 and the firstaxis A. In other words, at least a portion of the nozzle 210 elongatingalong the first axis A may be enclosed by the cylinder-shaped wheelwhich is configured to rotate around the nozzle 210. The wheel of theprinter head 100 may be configured to be brought into abutting contactwith at least one peripheral edge 280 of the at least one layer duringoperation of the printer head 200, and may hereby rotate when guidedalong the at least one peripheral edge 280 of the at least one layer250. It will be appreciated that the wheel may comprise, or consist of,one or more materials which properties are beneficial for the ability ofthe wheel to smoothen out the deposited layer(s) 250. For example, thematerial(s) of the wheel may provide a relatively low frictioncoefficient between the wheel and the layers 250, a relatively lowsurface energy (i.e. a non-sticky surface) and/or a relatively high heatresistance. Examples of materials of the wheel may bepolytetrafluoroethylene (PTFE), graphite, or the like.

FIG. 3 is a schematic view of a printer head 300 according to anexemplifying embodiment of the present invention. Here, the nozzle 310of the printer head 300 elongates along a first axis A, wherein aportion of the exterior surface of the nozzle 310 has the form of aplane B which is parallel to the first axis A. Furthermore, the exteriorsurface of the nozzle 310 comprises at least one surface area 330 of aspherical sector of the nozzle 310, wherein the spherical sector hasangle α and radius r.

FIG. 4 is a schematic view of a printer head 400 and a smoothening oflayers 410 of an object 420, according to an exemplifying embodiment ofthe present invention. The printer head 400 of the 3D-printing apparatus(not shown) has deposited a plurality of adjacently arranged filamentsof printing material to form a plurality of layers, which in turnconstitute an object 420 produced by the 3D-printing apparatus. Thenozzle 450 of the printer head 400 elongates along a first axis A andhas substantially the shape of a cylinder. After the creation of one ormore layers 410 of the object 420, the nozzle 450 of printer head 400has been brought into abutting contact with the peripheral edge of theat least one layer 410 of the object 420. The nozzle 450 is thereafterguided in the circumferential direction G along at least a portion ofthe peripheral edge of the layer(s) 410. In other words, each printedlayer 410 is smoothed by pressing the smooth, vertical surface of thenozzle 450 against the outer, vertical wall of the printed object 420.During this process, the nozzle 450 does not dispense any printingmaterial. Furthermore, the nozzle 450 may be configured to penetrate apredetermined distance into the at least one layer 410. It will beappreciated that the nozzle 450 may be cooled at least during theguiding of the nozzle 450 in the circumferential direction G.

FIG. 5 is a schematic flow chart diagram of a method 500 according to anexemplifying embodiment of the present invention. The method 500comprises the step 510 of providing a 3D-printing apparatus comprising aprinter head according to any one of the previously describedembodiments. The method 500 further comprises the step 520 of depositingone or more adjacently arranged filaments of printing material to format least one layer of an object to be produced. The method 500 furthercomprises the step 530 of bringing at least one exterior surface of thenozzle into abutting contact with the peripheral edge of the at leastone layer. Furthermore, the method 500 comprises the step 540 of guidingthe nozzle along at least a portion of the peripheral edge of the atleast one layer and on a predetermined distance d into the at least onelayer.

The person skilled in the art realizes that the present invention by nomeans is limited to the preferred embodiments described above. On thecontrary, many modifications and variations are possible within thescope of the appended claims. For example, it will be appreciated thatthe figures are merely schematic views of printer heads according toembodiments of the present invention. Hence, any elements/components ofthe printer heads 200, 300, 400 and/or nozzles 210, 310, 450 may havedifferent dimensions, shapes and/or sizes than those depicted and/ordescribed.

1. An extrusion-based additive manufacturing method for manufacturing anobject using a 3D-printing apparatus, wherein the 3D-printing apparatuscomprises a nozzle arranged to deposit one or more adjacently arrangedfilaments of printing material, and wherein the method comprises thesteps of: depositing the one or more adjacently arranged filaments ofprinting material to form at least one layer of the object, bringing atleast one exterior surface of the nozzle into abutting contact with aperipheral edge of the at least one layer; and guiding the nozzle alongat least a portion of the peripheral edge of the at least one layer andon a predetermined distance into the at least one layer.
 2. The methodaccording to claim 1, wherein the nozzle elongates along a first axis A,and wherein the method further comprises the step of: guiding the nozzlea predetermined distance along the first axis.
 3. The method accordingto claim 1, further comprising the step of: cooling the nozzle at leastduring the step of guiding of the nozzle along the peripheral edge ofthe at least one layer and on a predetermined distance into the at leastone layer.
 4. A computer program comprising instructions which, when theprogram is executed by a 3D-printing apparatus, cause the 3D-printingapparatus to carry out the steps of the method according to claim
 1. 5.A computer-readable data carrier having stored thereon the computerprogram of claim 4.